1. Field of the Invention
This invention relates to basic electrical devices; namely, solenoids comprising an electrically energized coil surrounding a plunger. Solenoids convert electrical energy into mechanical energy associated with linear motion. Solenoids can be of the push or pull type.
2. Description of Related Art
Solenoids have long been known in the electrical art. The basic electrical design principle of solenoids is simple and involves assembling an electrically energized coil wound on a spool body and surrounding either a plunger or a fixed core.
The magnetic force owing to the ampere windings of the coil exert an attraction on the plunger. When these ampere windings of the coil are energized, a magnetic force is exerted on the plunger. The plunger, responding to the influence of the coil's magnetic field typically is designed to slide into the axial tubular passage defined by the coil windings and spool body.
It has been known in the prior art to place an iron or steel casing around the coil. The iron or steel casing or can provides an enhanced magnetic return circuit. The mechanical force that the plunger can exert is increased particularly toward the end of the plunger's stroke. An electromagnetic attraction is exerted between the can and the end of the plunger. The can-encased solenoid has been the conventional solenoid in this art for well over forty years.
A need has existed in the art for a solenoid having simplified assembly. If some assembly step could be eliminated, production would be increased with a resulting lower unit cost.
It is an object of the present invention to disclose an improvement over the conventional steel can encased solenoid.
It is an object of the present invention to disclose a solenoid having a metal-filled polymer as the magnetic return circuit. It is a further object to disclose a solenoid with a metal-filled polymer as the magnetic return circuit which can be injection molded.